Species Description: Uyeda JC, Drewes RC, Zimkus BM 2007 The California Academy Sciences Gulf of Guinea Expeditions (2001, 2006) VI. a new species of Phrynobatrachus from the Gulf of Guinea Islands and a reanalysis of Phrynobatrachus dispar and P. feae (Anura: Phrynobatrachidae). Proc. Calif Acad Sci 4 ser 58:367-385
© 2007 Robert C. Drewes (1 of 3)
DESCRIPTION OF THE HOLOTYPE.— CAS 218901 Male, 15.5mm SVL; total length of the leg is 1.5–2.0 times the SVL. Width of the head greater than 2.5 times the diameter of the eye. Dorsal asperities are indistinct to the naked eye and are most numerous between the posterior half of the eyelid and the tibio-fibula. However, a few asperities extend beneath the eye and onto the snout as well as the anterior portion of the eyelid. Tympanum indistinct, less than half the width of the eye. Two indistinct glandular ridges topped with 3 to 4 white-pointed asperities forming a broken X-shaped pattern are located on the mid-dorsum. The gular sac is darkened and appears as an inverted “U” shaped patch on the throat. The anterior border of the dark pigment contains numerous spicules that extend from the very tip of the lower jaw posterior to the corners of the mouth. These are found in 5–7 rows on the tip of the jaw and narrow to only 1–2 rows at the angle of the jaw. The medial lingual papilla on the tongue is present. Femoral glands, although indistinct, are present in the middle of the thigh; the glands extend about one-fourth the total length of the thigh. Webbing between fingers absent, webbing between toes reduced and deeply incised, existing mostly as a narrow fringe on the sides of the toes, webbing formula I2-3II3-–3+III3+-4+IV5-–4-V (Savage and Heyer 1997). Distal phalanx T-shaped, resulting in the appearance of dilated toe tips.
COLOR IN PRESERVATIVE.-Dorsum ground color a dark grayish-brown, lacking many distinctive markings. Two dark blotches over the front legs extend diagonally toward the eye. Faint light inter-orbital stripe followed by a faint dark patch in the center of the dorsum behind the eyes. Indistinct dark splotches are present on the dorsum. Only one or two faint dark bars are found on either the thigh or the tibio-fibula of the hind limb. Ventrum pale cream-colored and clear except for the throat and a few darkly pigmented spots extending along the flanks to just beyond the front legs. Seven distinct dark brown bars line the lower jaw. Undersides of the hind limbs clear, slight yellowish hue.
Distribution and Habitat
Country distribution from AmphibiaWeb's database: Sao Tome and Principe
Relation to Humans
Sequence data demonstrate considerable divergence between the two island species of Phrynobatrachus. Using a low estimate of divergence of 19% for the cytochrome b gene and a molecular clock estimate as high as 1.4% sequence divergence per million years, a value considerably higher than estimated divergence rates found in other amphibians (Caccone et al. 1997; Veith et al. 2003), suggests a time of divergence that predates the estimated origin for São Tomé of 13 million years ago (Lee et al. 1994). This would seem to suggest that the most likely scenario for the divergence of the two species would be independent colonizations from mainland Africa. After the recognition into two Phrynobatrachus species, each endemic to a single island, only one species of amphibian, Hyperolius molleri, appears to have successfully dispersed from one island to the other (or recently colonized both islands). However, it is difficult to make conclusions with any certainty given the unreliability of molecular clock estimates, the uncertainty of the sequence divergence, and the possibility that the estimated age of São Tomé may actually be much greater than 13 million years (orogeny dates were based upon the oldest lava flows, which only set a minimum age for the island). Analyses of 12S rRNA, valine-tRNA, and 16S rRNA-mtDNA further support the divergence between the two island species of Phrynobatrachus as intra-island variability was low in comparison to interspecific divergence.
Surprisingly, a number of recent molecular studies suggest that many of the endemic amphibians of the Gulf of Guinea islands may be more closely related to East African species than to their West African congeners; these studies include the fossorial caecilian, Schistometopum thomense (Wilkinson et al. 2003), Ptychadena newtoni (Measey et al. 2007) and, perhaps the treefrogs, Hyperolius molleri and H. thomensis. (Drewes and Wilkinson 2004, show the closest outgroup relative to be H. cinnamomeoventris, whose range includes East Africa). Similar claims have been made for the endemic terrestrial gastropod mollusk, Bocageia (Gascoigne 1994). Whereas this pattern may be a reflection of poor sampling in the intervening Congo Basin, the inclusion of the larger dataset (BMZ) in this study (12 Phrynobatrachus species) seems to support a Gulf of Guinea island-East Africa relationship. Phrynobatrachus dispar and P. leveleve consistently form a clade with Phrynobatrachus species from Ethiopia, Kenya, Malawi, and Tanzania (P. keniensis, P. inexpectatus, P. cf. minutus, P. parvulus, and P. rungwensis), rather than with the West African species P. calcaratus and P. cornutus. This curious pattern draws attention to the need for phylogenetic reconstruction of the Gulf of Guinea amphibians within the context of the African amphibian fauna, which may provide considerable data on the mechanisms and timing of colonization events. Currently such studies are limited by poor collections across Africa, especially the Congo Basin, and a paucity of researchers with an interest in African herpetofauna. We call attention to this deficit in the hopes that future researchers will take on the challenge of providing a comprehensive treatment of these species.
Excerpted with permission from:
The California Academy of Sciences Gulf of Guinea Expeditions (2001, 2006) VI. A new species of Phrynobatrachus from the Gulf of Guinea Islands and a reanalysis of Phrynobatrachus dispar and P. feae (Anura: Phrynobatrachidae) by Uyeda, J. C., Drewes, R. C., and Zimkus, B. M. (2007). Proceedings of the California Academy of Sciences, Vol. 58, pp. 367-385, 8 figs., Appendix (4 tables).
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Uyeda, J. C., Drewes, R. C. and Zimkus, B. M. (2007). ''A new species of Phrynobatrachus from the Gulf of Guinea Islands and a reanalysis of Phrynobatrachus dispar and P. feae (Anura: Phrynobatrachidae).'' Proceedings of the California Academy of Sciences, 58(18), 367-385.
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Wilkinson, M., Loader, S. P., Gower, D. J., Sheps, J. A., and Cohen, B. L. (2003). ''Phylogenetic relationships of African caecilians (Amphibia: Gymnophiona). Insights from mitochondrial rRNA gene sequences.'' African Journal of Herpetology, 52, 83-92.
Written by Michelle Koo (mkoo AT berkeley.edu), Museum of Vertebrate Zoology, University of California
First submitted 2008-01-02
Edited by Kellie Whittaker (2010-10-29)
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